Vitamin D DeficiencyFam-D-BreadNCT07481240
A Household-Based Dietary Intervention Study of Vitamin D Fortified Bread in Irish Families
A study testing Fortified Bread and Unfortified bread in people with Vitamin D Deficiency, run by University College Cork at 2 sites in Ireland.
Trial summary
Vitamin D deficiency is common. It is caused by limited sun availability together with a low supply of vitamin D in the food system. There is a high prevalence of low vitamin D status around the world. Read more about this study
- Who is it for?
- Ages 5 to 59 yearsHealthy volunteers can take part
- Conditions the study is for
- Vitamin D Deficiency
- What is being tested?
- Fortified Bread and Unfortified bread
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 128 participants
- Where
- 2 sitesIreland
- Study dates
- 17 Nov 2025to 4 Apr 2026
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 5 to 59 years
- All sexes
- Healthy volunteers accepted
- Child, Adult
Who may be able to join
- Provide written informed consent if over 16 years; informed parental consent for children under-16 years, plus age-appropriate assent for children under-16 years.
- Be a household with at least one adult ≥18 years, with at least one dependent aged 5 years or older.
- Willing to consume bread provided and have storage capacity for frozen bread.
- Be in good general health.
- Be willing to follow the assigned diet for 8 weeks and attend the required appointments.
Who cannot join
- Daily consumption of a vitamin D supplement with a dose exceeding >10µg/d (400 IU) equivalent.
- Exposure to factors that may influence vitamin D status, such as winter sun holiday, ski holiday, tanning beds etc.
- Are following a medically prescribed diet.
- Have a diagnosis of a medical condition that may interfere with vitamin D absorption, such as Coeliac disease, Inflammatory Bowel Disease, cystic fibrosis, or metabolism, such as liver disease, renal disease.
- Have a history of active cancer or a diagnosis of cancer within the past 5 years.
- Have an allergy to the bread ingredients.
- Are participating in another research study with an intervention or other lifestyle programme that would interfere with the outcomes of the study.
- Are unable to read, write, or understand English.
Trial locations and contacts
2 sites in 1 country.
Ireland2 sites
Human Nutrition Studies Unit, School of Food and Nutritional Sciences
Cork, Co. Cork, T12 K8AF
UCD Institute of Food and Health
Dublin
About this study
Official title: Fam-D-Bread: A Household-Based Dietary Intervention Study of Vitamin D Fortified Bread in Irish Families
Vitamin D deficiency is common. It is caused by limited sun availability together with a low supply of vitamin D in the food system. There is a high prevalence of low vitamin D status around the world. In Ireland, our relatively northern latitude and prevailing weather mean that UVB availability for skin synthesis of vitamin D is limited in this country and our population relies on the dietary supply of vitamin D to prevent deficiency. Thus, the endemic Irish problem of vitamin D malnutrition is due to the lack of vitamin D in our food system. Dietary guidelines cannot address this issue because foods naturally rich in vitamin D are very few and infrequently consumed.
The FamDBread study will test the hypothesis that a vitamin D-fortified bread as part of a healthy diet that includes vitamin D-fortified foods is effective in preventing low vitamin D status during winter, and safe for families to consume.
Read the detailed description
This randomised controlled dietary intervention study aims to recruit households/families of children, teens and adults, with 128 participants who will be randomised to receive vitamin D-fortified bread and advice to consume additional commercially available fortified foods (Treatment group) or identical unfortified bread and advice to consume additional commercially available fortified foods (Control group). The outcome of the study is to test whether increasing vitamin D intake through food (Treatment group) is sufficient to prevent wintertime vitamin D deficiency (measured using serum concentrations of 25-hydroxyvitamin D <30 nmol/L) in comparison with the Control group.
The target vitamin D intake for the treatment group in this study is >20 μg/ day vitamin D. This will maintain serum concentrations of 25-hydroxyvitamin D (25(OH)D) (the biomarker of vitamin D status) > 30 nmol/L, the clinical deficiency threshold to prevent metabolic bone disease, in over 90% of participants. At this vitamin D intake level, about 80% of participants will have a 25(OH)D concentration > 50 nmol/L, the personal intake target in the US and EU.
- Conditions
- Vitamin D Deficiency
- Being tested
- Fortified Bread, Unfortified bread
- Medical subject headings
- Vitamin D Deficiency
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Fortified BreadOther
Intervention group will be supplied with fortified bread delivering >20 μg vitamin D3 in a daily portion and will receive dietary advice to incorporate fortified foods that are commonly available on the market in their diet.
Unfortified breadOther
Placebo control group will be supplied with unfortified bread and will receive dietary advice to incorporate fortified foods that are commonly available on the market in their diet.
| Study group | Role | What they receive |
|---|---|---|
| Fortified bread Intervention group | Experimental | Fortified bread Intervention group will be supplied with vitamin D fortified bread. Fortified Bread Intervention group will be supplied with fortified bread delivering >20μg vitamin D3 in a daily portion and will receive dietary advice to incorporate fortified foods that are commonly available on the market in their diet. Receives: Other: Fortified Bread |
| Placebo Comparator | Placebo comparator | Control arm will receive unfortified bread and dietary advice to incorporate fortified foods that are commonly available on the market in their diet. Receives: Other: Unfortified bread |
What is being measured
The primary outcome is the main question the study is designed to answer.
Serum concentrations of 25-hydroxyvitamin D (25(OH)D)
Comparison of the number of participants with low vitamin D status (e.g. <30 nmol/L and < 50 nmol/L serum 25(OH)D) between treatment and placebo groups
Measured: 8 weeks
Secondary outcomes (3)
Vitamin D intakes
Comparison of prevalence of inadequate vitamin D intakes relative to North American and European dietary recommendations
Measured: 8 weeks
Serum concentrations of albumin-corrected serum calcium concentrations as a safety measure
Comparison of albumin-corrected serum calcium concentrations < 2.6 mmol/L between treatment and placebo control groups
Measured: 8 weeks
Circulating biomarkers of metabolic health status
Comparison of circulating biomarkers of metabolic health status and metabolomic markers between active and placebo groups
Measured: 8 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted18 Mar 2026
- Study start17 Nov 2025
- Primary completion4 Apr 2026
- Study completion4 Apr 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Vitamin D DeficiencyStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- Parallel Assignment
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 128 participants (actual)
Sponsor and investigators
- Lead sponsor
- University College Cork
- Sponsor type
- University, hospital or other
- Collaborators
- University College Dublin
- Responsible party
- Principal investigator, Mairead Kiely PhD, University College Cork
- Investigators
- Mairead Kiely, PhD, Principal investigator, University College Cork
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07481240
- Sponsor's protocol ID
- FamDBread_22122
- Acronym
- Fam-D-Bread
- Status last verified
- May 2026
- First submitted
- 13 Mar 2026
- Last updated
- 15 May 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Please contact m.kiely@ucc.ie for any queries related to data access
Study at a glance
From the registry record, last updated by the sponsor on 15 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Fam-D-Bread: A Household-Based Dietary Intervention Study of Vitamin D Fortified Bread in Irish Families
- ClinicalTrials.gov ID
- NCT07481240
- Acronym / sponsor ID
- Fam-D-Bread / FamDBread_22122
- Conditions
- Vitamin D Deficiency
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 128 participants (actual)
- Lead sponsor
- University College CorkUniversity, hospital or other
- Collaborators
- University College Dublin
- Study start
- 17 Nov 2025 (actual)
- Primary completion
- 4 Apr 2026 (actual)
- Study completion
- 4 Apr 2026 (actual)
- First posted
- 18 Mar 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Vitamin D deficiency is common. It is caused by limited sun availability together with a low supply of vitamin D in the food system. There is a high prevalence of low vitamin D status around the world. In Ireland, our relatively northern latitude and prevailing weather mean that UVB availability for skin synthesis of vitamin D is limited in this country and our population relies on the dietary supply of vitamin D to prevent deficiency. Thus, the endemic Irish problem of vitamin D malnutrition is due to the lack of vitamin D in our food system. Dietary guidelines cannot address this issue because foods naturally rich in vitamin D are very few and infrequently consumed.
The FamDBread study will test the hypothesis that a vitamin D-fortified bread as part of a healthy diet that includes vitamin D-fortified foods is effective in preventing low vitamin D status during winter, and safe for families to consume.
Detailed description
This randomised controlled dietary intervention study aims to recruit households/families of children, teens and adults, with 128 participants who will be randomised to receive vitamin D-fortified bread and advice to consume additional commercially available fortified foods (Treatment group) or identical unfortified bread and advice to consume additional commercially available fortified foods (Control group). The outcome of the study is to test whether increasing vitamin D intake through food (Treatment group) is sufficient to prevent wintertime vitamin D deficiency (measured using serum concentrations of 25-hydroxyvitamin D <30 nmol/L) in comparison with the Control group.
The target vitamin D intake for the treatment group in this study is >20 μg/ day vitamin D. This will maintain serum concentrations of 25-hydroxyvitamin D (25(OH)D) (the biomarker of vitamin D status) > 30 nmol/L, the clinical deficiency threshold to prevent metabolic bone disease, in over 90% of participants. At this vitamin D intake level, about 80% of participants will have a 25(OH)D concentration > 50 nmol/L, the personal intake target in the US and EU.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 2
- Model description
- Parallel Assignment
| Arm | Type | Receives |
|---|---|---|
| Fortified bread Intervention group | Experimental | Other: Fortified BreadFortified bread Intervention group will be supplied with vitamin D fortified bread. Fortified Bread Intervention group will be supplied with fortified bread delivering >20μg vitamin D3 in a daily portion and will receive dietary advice to incorporate fortified foods that are commonly available on the market in their diet. |
| Placebo Comparator | Placebo comparator | Other: Unfortified breadControl arm will receive unfortified bread and dietary advice to incorporate fortified foods that are commonly available on the market in their diet. |
Who may qualify
- Ages
- 5 to 59 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Child, Adult
Key inclusion criteria (5 listed)
- Provide written informed consent if over 16 years; informed parental consent for children under-16 years, plus age-appropriate assent for children under-16 years.
- Be a household with at least one adult ≥18 years, with at least one dependent aged 5 years or older.
- Willing to consume bread provided and have storage capacity for frozen bread.
- Be in good general health.
- Be willing to follow the assigned diet for 8 weeks and attend the required appointments.
Key exclusion criteria (8 listed)
- Daily consumption of a vitamin D supplement with a dose exceeding >10µg/d (400 IU) equivalent.
- Exposure to factors that may influence vitamin D status, such as winter sun holiday, ski holiday, tanning beds etc.
- Are following a medically prescribed diet.
- Have a diagnosis of a medical condition that may interfere with vitamin D absorption, such as Coeliac disease, Inflammatory Bowel Disease, cystic fibrosis, or metabolism, such as liver disease, renal disease.
- Have a history of active cancer or a diagnosis of cancer within the past 5 years.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Fortified BreadIntervention group will be supplied with fortified bread delivering >20 μg vitamin D3 in a daily portion and will receive dietary advice to incorporate fortified foods that are commonly available on the market in their diet. | Other | Fortified bread Intervention group |
| Unfortified breadPlacebo control group will be supplied with unfortified bread and will receive dietary advice to incorporate fortified foods that are commonly available on the market in their diet. | Other | Placebo Comparator |
Primary outcome
Serum concentrations of 25-hydroxyvitamin D (25(OH)D)
Time frame: 8 weeks
Comparison of the number of participants with low vitamin D status (e.g. <30 nmol/L and < 50 nmol/L serum 25(OH)D) between treatment and placebo groups
3 secondary outcomes
Vitamin D intakes
Time frame: 8 weeks
Serum concentrations of albumin-corrected serum calcium concentrations as a safety measure
Time frame: 8 weeks
Circulating biomarkers of metabolic health status
Time frame: 8 weeks
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 15 May 2026.
- Individual participant dataSharing planned: No. Please contact m.kiely@ucc.ie for any queries related to data access
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Mairead Kiely, PhD principal investigator
University College Cork
2 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Fortified Bread and Unfortified bread in people with Vitamin D Deficiency, run by University College Cork at 2 sites in Ireland.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 8 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 15 May 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 2 sites in Ireland. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Serum concentrations of 25-hydroxyvitamin D (25(OH)D) (time frame: 8 weeks). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 15 May 2026.